Process for desludging phosphating baths and device for carrying out said process

US4968360A · kind A · utility

Assignee

• Gerhard Collardin GmbH · DE

Inventors

• Kurt Hosemann · Titz, DE
• Karl-Heinz Gottwald · Lechenich, DE
• Willi Wuest · Ratingen, DE
• Hubert Harth · Goldkronach, DE

Key dates

• Filing date: Dec 13, 1988
• Grant date: Nov 6, 1990
• Expiry date: Dec 13, 2008

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C23C22/86
• WIPO field: Surface technology, coating
• WIPO sector: Chemistry

Abstract

The development of sludge in phosphating baths is prevented by continuously diverting a partial volume of the baths into a separate device comprising three open chambers: an oxidation chamber where the solution is treated with an O.sub.2 -containing gas to oxidize the iron (II) of the solution of iron (III), which precipitates as phosphate; a conditioning chamber in which the iron (iii) phosphate precipitate formed in the oxidation chamber is agglomerated into a readily sedimented form; and a sedimentation chamber in which the sediment formed in the conditioning chamber is separated from the remaining liquid phosphating solution. This solution is then replenished with phosphate layer-forming components, and the replenished solution is subsequently recycled to the phosphating bath.